Rheostat



Jan. 21, 1925. H

A. A. KENT RHEOSTAT Filed April 25, 1923 INVENTOR. M M M ATTORNEY:

1,524,258 PATENT OFFICE.

ARTHUR All-WATER KENT, OF ABDMORE, PENNSYLVANIA.

BHEOSTAT.

Application filed April 25, 1923. Serial No. 634,450.

To all whom it may comer n:

Be it known that I, ARTHUR ATWATER KENT, a citizen of the United States, residing at Ardmore, county of Montgomery, and State of Pennsylvania, have invented certain new and useful Improvements in Rheostats, of which the following is a specification.

My invention relates to adjustable resistances or rheostats having general use or application in the electrical arts for varying or adjusting the resistance of a circuit.

In accordance with my invention there is provided a multiple point engagement between handle, knob or cap and the base or fixed member of the rheostat; and the sta tionary contact which engages the resistance conductor when that conductor is carried by the handle, knob or cap, may be one of the multiple points of engagement or suport. p The structure embodying my present invention is of the character disclosed in my co-pending application, Serial No. 631,987, filed April 14, 1923;

My invention resides in rheostat structure of the character hereinafter described and claimed.

For an illustration of one of the various forms my invention may take, reference is had to the accompanying drawing, in which:

Fig. 1 is a top plan view of structure embodying my invention.

Fig. 2 is a plan view, partly in section, of the structure of Fig. 1 with the cap removed.

Fig. 3 is a vertical sectional view on the line 3-3 of Fig. 1.

Fig. 4 is a. bottom plan view of the structure shown in Figs. 1, 2 and 3. V

Fig. 5 is a bottom plan view of the cap and associated resistance unit.

Referring to the drawing, 1 is the base, fixed member or stationary structure which may be, as illustrated. the end closure of a casing having the side wall 2, preferably molded integral with the base 1, of any suitable insulating material, as, for example bakelite or condensite. The members 1 and 2 form a hollow base which may be provided with the integral lugs 3 for attachment to any suitable support, as by screws extending through the holes 4.

Disposed above the base 1 is the handle,

knob, cap or operating member 5, preferably of molded insulating material, having the integral annular flange or rib 6 forming the inner boundary of an annular groove or channel 7, within which is disposed and carried by the member 5 the resistance unit or conductor 8, of any suitable character or form, but preferably, as indicated, in

the form of a coreless helix of bare resist-ance wire which is preferably slightly compressible or yielding radially, as upon application of pressure thereto by the fixed co-acting contact 9, which may itself be a yielding contact or, as indicated, may be a rigid contact. The contact 9 is carried or fixed upon the base 1 and has a portion 10 extending to the opposite side of the base 1 and there connected by conductor 11 with the binding post 12 carried by the side wall 2 of the casing. One end 8 of the resistance conductor 8 is led through a slot 13 in the rib or flange 6 to the metallic post or stub shaft 14 and soldered or otherwise suitably well electrically connected therewith. The shaft 14 is carried by the cap 5 and is preferably molded therein, and its free portion extends through and to the opposite side of the base 1, forming a bearing or centering means for the rotatable cap 5. Projecting upwardly from the base 1 are the bosses or studs 15, preferably integral with the base 1 and engaged by that portion of cap 5 outside of the-groove 7, the studs 15 preferably being of equal height and serving with the fixed contact 9 as a three-point support or engagement for the cap or handle 5 upon the base or fixed structure, preventing the cap or handle from materially tilting.

The shaft 14 at its lower end has the annular groove or notch 16, in which engages the forked end 17 of the 8 ring contact member 18, turned downwar y at its outer end and connected to the second binding post 19. The spring 18 exerts a downward pull or bias upon the shaft 14, and therefore upon the cap 5 and the resistance unit 8 carried thereby, causing the cap to bear upon the studs 15 and the resistance unit 8 to bear upon the fixed contact 9. As indicated in Fig. 3, it is preferred that the spring 18 be so positioned with respect to the fixed contact 9 that the downward force exerted by the spring 18 upon the cap 5 or the entire movable structure tends to press, through the intermediate resistance unit 8, upon the fixed contact 9, thereby always ensuring good contact between the fixed contact 9 and the resistance conductor, any looseness or play between the shaft 14. and the walls of the aperture in the base 1 through which the'shaft extends premitting such slight tilting of the cap 5 as will effect this result. For this purpose the contact spring is preferably disposed on that side of the shaft 14 opposite to the contact 9, or more generally speaking. is within the semi-circle opposite to the semi-circle at the arcuate middle of which the contact 9 is positioned.

Carried by the cap 5 is the pin or stud 20, into whose rotary path of travel extend the aforesaid studs 15, whereby the extent of rotation of the cap 5 is limited to correspond substantially with the sweep over the conductor 8 of the contact 9.

I In operation, the operator grasps the knob or handle 5 and rotates it, therebyrotating the resistance conductor 8 with respect tov the contact 9, thereby varying or adjusting the amount of resistance in circuitbetween the bindingfposts 12 and 19, the knob or handle riding upon the three-point support or suspension comprising the two studs 15 and the contact 9, which latter serves both as a point of support or suspension and a contact for effecting electrical engagement with the conductor 8.

' It shall be understood that my invention is, not limited to the employment of the multiple point suspension or support hereinbefore described, for some features of my invention are present when the ca 5 otherwise rides or bears upon the fixe structure or base 1. e

What I claim is: I 1. Rheostat structure comprising a fixed base and a cap rotatable relatively thereto,

and projecting members forming at least three points of support for said cap upon "said base.

3. Rheostat structure comprising a base and a rotatable cap, a resistance member and a co-acting relatively rotatable contact memher, one ofsaid members carried by said base and the other carried by said cap, projecting members forming at least three said cap toward said base.

points of support for said cap upon said base, and means for biasing said cap towards said base. i

4. Rheostatstructure comprising a base and ar'otatable cap. a resistance member and a co-acting relatively rotatable contact member, one of said members carried by said base and the other carried by said cap, means forming at least three points of support for said cap upon said base, one of said points of support being effected by the enga ement with each other of said resistance ant contactmembers' 5. Rheostat structure comprising a-base and a rotatable cap, a resistance member and a co-actingrelatively rotatable contact member, one of saidv members carried by said base and the other carried by said cap, means forming at least three points o'fsupport for said cap upon said base, one of said points of support being effected by the engagement with each other of said resistance and contact members, and means for biasing 6. Rheostat structure comprising a base and a rotatable cap, a resistance member and a co-acting relatively rotatable contact member, one of said members carried by said base and the other carried by said cap, means forming at least three points of support for said cap upon said base, one of said points of support being effected by the engagement with each other of said resistance and contact members, and means biasing said cap towards said base and so positioned with respectto said contact member as to tilt said cap toward the contact between said resistance member and said contact member. 7 Rheostat structure comprising a base and a rotatable cap, a resistance member in the form of an arcuate helix carried by said cap, a co-acting contact carried by said base, means forming at least three points of support for said cap upon said base, one of said points of support being an engagement betweensaid hslix andlslaid contact, a shaft engaging sai .cap, an as rmg en 'a said shaft to bias said cap tgward said is: and so positioned as to tend to tilt said cap toward said contact. I

8. Rheostat structure comprising a base and rotatable cap, a resistance member and a c0-acting relatively rotatable contact member, one of said members carried by said base and the other carried by said cap, and a plurality of studs on said base against which said cap bears, engagement between said contact and resistance members forming with said studs a multiple point support for said cap.

9. Rheostat structure comprising a base and rotatable cap, a resistance member and a co-acting relatively rotatable wntact member, one of said members carried by said base and the other carried by said cap,

a plurality of studs on said base against which said cap bears, engagement between said contact and resistance members forming with said studs a multiple point support for said cap, and means on said cap in whose path of travel one of said studs is disposed for limiting the'rotation of said cap.

10. Rheostat structure comprising a fixed base member and a relatively rotatable cap member, said cap member having an annular groove, a resistance member disposed in said groove, a co-acting contact member carried by said base member, and a plurality of circumferentially spaced projections formin points of engagement between said cap and base members at a distance from the axis of rotation of said cap member greater than the distance of said groove from said axis.

11. Rheostat structure comprising a fixed base member and a relatively rotatable cap member, said cap member havin an annular groove, a reslstance member isposed in said groove, a co-aeti'ng contactmember carried by said base member, and a plurality of circumferentially spaced projections forming points of engagement between said cap and base members at a distance from the axis of rotation of said cap member ARTHUR ATWATER KENT. 

